The present invention relates to an adjustable handlebar stem for bicycles, mopeds, motorcycles and all steerable devices which utilize a steering principle similar to that of a bicycle. More specifically, the invention relates to a simultaneous handlebar height and forward/backward position joint adjustment means which can be locked.
Previously, a bicycle has usually been equipped with a handlebar stem which has only the possibility of straight up and down adjustments. However, special adjustable handlebar stem devices of various types are previously known and are adapted for various purposes. Recently however, some handlebar stem manufacturers have in addition made it possible to vary the length of protrusion of a handlebar stem. The result is that the handlebar may be placed in almost any position. When the position of the handlebar is to be varied, the handlebar itself must also be rotated in order that the brake handles fall into the hands of a rider in a natural and ergonometrically correct manner. In order to adjust the handlebar with the previously known handlebar stem devices, it is necessary first to loosen three bolts, thereafter to move the handle bar into the desired position, and then to refasten the same three bolts. The three bolts have the following respective purposes: a) adjustment of the bicycle handlebar up and down, b) adjustment of protrusion in directions toward or away from the bicyclist, and c) rotation of the handlebar itself around the handlebar main axis.
From Belgian Patent No. 523,314 is previously known a device having certain qualities in common with the present invention, namely an adjustable device using two parallel arms movable about bearing points and which can be locked in a stepless manner by means of a wing nut in one of the bearing points in order to provide a handlebar adjustment substantially in height. The travel of the handlebar is from an upper extreme position, downward and forward, and thereafter further downward and backward again to a lower extreme position. Such parallelogram guiding of the handlebar maintains the handlebar orientation in a vertical plane, i.e. the rotational orientation of the handlebar around the handlebar main axis is maintained through the entire movement of the handlebar.
For quite some time the possibility of varying the body posture during cycling has been considered desirable. In other words, there has been a need for a simple and practical device on the bicycle for providing such a possibility. In the first place it is uncomfortable to sit in the same position for a long time while cycling. Secondly, by varying the sitting posture on the bicycle, more effective cycling is achieved. When bicycling uphill, or possible when bicycling at a higher speed on the flat, it is often found more efficient for the handlebar to be in a low and relatively far advanced position. However, when bicycling in dense traffic where a good view is necessary, it is often found most appropriate to sit in a relatively high and upright posture.